Docs: convert some component config to zuul directives

This updates common and scheduler.

Also adds a note to the docs style guide about booleans because
I was reminded of it while I was updating this.

Change-Id: I56b3e3c8f99548887056b881f9b3d77e9f45b275
diff --git a/doc/source/developer/docs.rst b/doc/source/developer/docs.rst
index cce4ca3..6a7256e 100644
--- a/doc/source/developer/docs.rst
+++ b/doc/source/developer/docs.rst
@@ -20,6 +20,11 @@
 a specific string into a configuration file) should use the RST
 ````literal```` syntax.
 
+YAML supports boolean values expressed with or without an initial
+capital letter.  In examples and documentation, use ``true`` and
+``false`` in lowercase type because the resulting YAML is easier for
+users to type and read.
+
 Terminology
 ~~~~~~~~~~~